Australia's Ashleigh Barty and France's Richard Gasquet reached the semi-finals in their respective events after winning their quarterfinal clashes at the Cincinnati Masters.

In women' singles, Barty moved closer to regaining the world number one ranking by beating Maria Sakkari 5-7, 6-2, 6-0 in her quarterfinal clash on Friday.

With one more win, she can move into the top spot for the US Open, taking it back from Japan's Naomi Osaka, who had much bigger concerns after dropping out of her semifinal match because of a knee injury.

After splitting sets with Sofia Kenin, Osaka took a timeout early in the third set to have her left knee examined and wrapped. She played only two more points before retiring, sending Kenin into the semifinals for the second straight week.